Convenient and accurate formulas for stress intensity factor distribution of semi-elliptical surface crack

In this paper, the stress intensity factor (SIF) formula F-ISE along the crack front of a semi-elliptical surface crack is studied. The exact SIF solution F-ISE is used by solving the hypersingular integral equation of the body force method discussed in the previous paper. To obtain the accurate formula, the SIF ratio F-ISE/F-IE is focused considering the exact solution F-IE of an elliptical crack. By applying the least squares method to the ratio F-ISE/F-IE, accurate and convenient formula is proposed. The proposed formulas may provide the accurate SIF distributions for the aspect ratio a/b = 1-4 better than 0.2% accuracy.